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Measuring Higgs boson couplings at the LHC

D. Zeppenfeld, R. Kinnunen, A. Nikitenko, E. Richter-Was

TL;DR

This work analyzes how the LHC can measure Higgs boson couplings in the intermediate-mass, SM-like regime by exploiting multiple production and decay channels, including gluon fusion and weak boson fusion. It formulates a width-based approach to extract partial widths and couplings from cross-section measurements, using SU(2) universality and fermion mass relations to relate observables. The study finds that width and coupling ratios can be determined at the 10–20% level with ~200 fb^{-1} of data, and that an absolute HWW coupling (and hence the total width) can be probed via weak-boson-fusion channels for m_H ≳ 120 GeV, albeit with substantial theoretical and background uncertainties. The results highlight the essential role of WBF channels and the need for further detector-level studies to refine background estimates and fully exploit Higgs coupling measurements at the LHC.

Abstract

For an intermediate mass Higgs boson with SM-like couplings the LHC allows observation of a variety of decay channels in production by gluon fusion and weak boson fusion. Cross section ratios provide measurements of various ratios of Higgs couplings, with accuracies of order 15% for 100 fb^{-1} of data in each of the two LHC experiments. For Higgs masses above 120 GeV, minimal assumptions on the Higgs sector allow for an indirect measurement of the total Higgs boson width with an accuracy of 10 to 20%, and of the H-->WW partial width with an accuracy of about 10%.

Measuring Higgs boson couplings at the LHC

TL;DR

This work analyzes how the LHC can measure Higgs boson couplings in the intermediate-mass, SM-like regime by exploiting multiple production and decay channels, including gluon fusion and weak boson fusion. It formulates a width-based approach to extract partial widths and couplings from cross-section measurements, using SU(2) universality and fermion mass relations to relate observables. The study finds that width and coupling ratios can be determined at the 10–20% level with ~200 fb^{-1} of data, and that an absolute HWW coupling (and hence the total width) can be probed via weak-boson-fusion channels for m_H ≳ 120 GeV, albeit with substantial theoretical and background uncertainties. The results highlight the essential role of WBF channels and the need for further detector-level studies to refine background estimates and fully exploit Higgs coupling measurements at the LHC.

Abstract

For an intermediate mass Higgs boson with SM-like couplings the LHC allows observation of a variety of decay channels in production by gluon fusion and weak boson fusion. Cross section ratios provide measurements of various ratios of Higgs couplings, with accuracies of order 15% for 100 fb^{-1} of data in each of the two LHC experiments. For Higgs masses above 120 GeV, minimal assumptions on the Higgs sector allow for an indirect measurement of the total Higgs boson width with an accuracy of 10 to 20%, and of the H-->WW partial width with an accuracy of about 10%.

Paper Structure

This paper contains 4 sections, 13 equations, 1 figure, 6 tables.

Table of Contents

  1. Introduction
  2. Survey of intermediate mass Higgs channels
  3. Measurement of Higgs properties
  4. Summary

Figures (1)

  • Figure 1: Expected accuracy with which the Higgs boson width can be measured at the LHC, with 100 fb$^{-1}$ of data in each experiment. Results are shown for the extraction of the the $H\to WW$ partial with, $\Gamma_W$, and and the total Higgs boson width, $\Gamma$. $\epsilon$ is the sum of the residual (small) branching ratios of unobserved channels, mainly $H\to c\bar{c}$ (see text for detail).